A guiding device disclosed in JP02-308313 A guides a vehicle to move to a target position set by a user on a setting screen, in which the guiding is carried out by creating in real time a target track (orbit) from the current position of the vehicle to the target position while estimating the current position of the vehicle, and by controlling a steering angle based on the created target track.
A guiding device disclosed in JP10-264839 A estimates the current position of the vehicle based on respective wheel speeds detected by wheel speed sensors and a yaw rate detected by a yaw rate sensor and judges whether the estimated current position of the vehicle departs from a target track. If the estimated current position departs from the target track, steering angles of the wheels are controlled according to the departure amount in order to correct the departure from the target track.
In order to guide a vehicle to a target position, it is required to monitor in real time a relationship between the current position of the vehicle and the target track during movement of the vehicle. This means that estimation of the current vehicle position plays an important role. Generally, the estimation of the current vehicle position is based on a controlled steering angle and a movement amount (moving distance) of the vehicle, that are detected, for instance, by a yaw rate sensor and a wheel speed sensor as in the aforementioned prior art. However, even in the case of steering angle being controlled precisely according to target steering angles, there is a difference between the estimated vehicle position and the actual vehicle position. The difference cannot be detected by a system, because steering angle is controlled precisely according to target steering angles. As a result of this, the difference is not corrected for and thus the vehicle is guided to the wrong. Therefore, it is desired to find the main factors causing such differences and compensate for the differences in order to improve the accuracy of the guiding control.